Directional well-drilling apparatus



April 30, 1968 R. P. VINCENT 3,330,543

DIRECTIONAL WELL-DRILLING APPARATUS Filed Jan. 19, 1966 3 Sheets-Sheet l RENIC P VINCENT INVENTOR.

Inf/ 4 I M AT TORNE Y.

April 30, 1968 R. P. VINCENT DIRECTIONAL WELL-DRILLING APPARATUS 3 Sheets-Sheet 2 Filed Jan. 19, 1966 RENIC F? VINCENT INVENTOR. BYMKM ATTORNEY.

April 30, 1968 R. P. VINCENT 3,380,543

DIRECTIONAL WELL-DRILLING APPARATUS Filed Jan. 19, 1966 5 Sheets-Sheet 5 FIG. 4

RENIC P. VINCENT INVENTOR.

BY/MA'WM ATTORNEY.

United States Patent 3.38% 543 DIRECTIONAL WELL-DiRILLlNG APPARATUS Renic P. Vincent, Tulsa, Okla, assignor to Pan American Petroleum Corporation, Tulsa, 81th., a corporation oi Delaware Filed Jan. 19, 1966, Ser. No. 521,704 7 Claims. ($1. 175-73) ABSTRACT OF THE DISCLQS'URE Apparatus for drilling straight wells includes at the bottom of a rotary drilling string a tubular spring joint, a stabilizer attached to the bottom of the spring joint, a universal joint below the stabilizer and the bit attached to the bottom of the universal joint. A side thrust mechanism may be included in the universal joint. The side thrust universal joint can be used alone for directional drilling. A particular universal joint havin very large bearing areas for transmitting thrust and torque is disclosed.

This invention relates to drilling wells. More particularly it relates to apparatus for use in a rotary drill string for preventing excessive deviation of the well from vertical, or correcting deviations which have already occurred. It also relates to apparatus for causing a well to deviate from vertical to the desired degree and in the desired direction.

In the rotary method of drilling wells, torque is applied to a hollow drill pipe extending down into the well to rotate a bit which drills the well. Ordinarily, heavy largediameter drill collars are used immediately above the bit. For various reasons, such as tilted hard formations, the well tends to deviate from a vertical position. This is particularly true when a high weight is carried on the bit to increase drilling rate. In some cases, it is desirable to avoid these deviations and drill a vertical hole. In other cases a deviated hole is desired but the natural direction of the deviation is not the direction which is wanted.

An o-b'ect of this invention is to provide apparatus for decreasing the deviation of the well from a vertical direction during drilling operations. Another object is to pro vide anparatus for causing the well to return to a vertical direction if it has deviated from this direction before use of the apparatus. Still another object is to provide apparatus which will permit a higher weight on the bit Without increa ing the angle of deviation of the Well from vertical while drilling proceeds. A more SDCCl1.C object is to provide a universal joint through which a very large torque and weight on bit can be transmitted from the drill collars to the bit. Still another object is to provide apparatus for causing a well to deviate from vertical to a desired ee and in the desired direction.

In general, I accomplish the objects of my invention which relate to drilling a vertical well by a combination of a tubular spring joint attached to the lower end of drill collars at the bottom of the well, a stabilizer below the tubular spring member, a universal joint below the stabilizer and the bit attached to the universal joint. The universal joint may have a side thrust mechanism associated with it to aid in turning the hit back toward vertical if the well deviates from this direction. A sealed passage is provided through the combination to conduct drilling fluid to the bit. The universal joint with the side thrust mechanism is used without the stabilizer and flexible tube joint for driving the well 01? vertical for directional drilling. The preferred universal joint for use in the combination has very large bearing surfaces for transmitting the thrust and torque necessary for drilling. his universal joint, of course, applications other than well drilling.

3,380,543 Patented Apr. 30, 1968 A better idea of the apparatus will be obtained from the drawings in which FIGURE 1 is a view showing the entire assembly including the spring joint, stabilizer and universal joint in rather diagrammatic form. FIGURE 2 is an exploded view of the three principal members of my universal joint. FIGURE 3 is a view in cross-section of my preferred form of the universal joint in assembled form. FIGURE 4 is a view, partly in cross-section of my preferred form of universal joint modified to contain the direction control mechanism.

In FIGURE 1 a well bore 11 has deviated from vertical so drill collars 12 lie against the lower wall of the well. Below the drill collars a tubular spring joint 13 connects the drill collars to a centralizer, sometimes called a stabilizer, 14 mounted on a mandrel 15. Below the stabilizer is a universal joint 16-. A bit 17 is attached to the lower end of the universal joint.

The stabilizer diameter should be very nearly the same as the diameter of the well bore. Therefore, the center of the stabilizer will be approximately at the center of the well bore. Since the drill collars 12 in an inclined hole are against the low side of the hole, the spring member I3 must bend. This bending tilts the axis of the stabilizer mandrel throwing the end of the mandrel attached to the universal joint, and the universal joint, above the center line of the wel bore and toward the upper side of the hole. The upper and lower parts of the universal joint must assume an angle with respect to each other since the center of the bit must be at the center of the bore hole while the upper end of the bit axis is displaced away from the bore hole center by the lower end of the stabilizer mandrel. The result is that the bit axis must assume an angle less than the angle of the bore hole axis with respect to vertical, thus pointing the bit back toward vertical.

Two very important features of this apparatus should be pointed out. First, is the requirement that a spring member be used above the stabilizer, and not some other flexible member such as a universal joint. Second, is the requirement that a universal joint be used below the stabilizer and not some other flexible member such as a spring joint.

Once a universal joint starts to buckle, it will continue to bend unless something stops it. In the apparatus shown in FIGURE 2, the degree of buckling of the universal joint is limited by two things. First is the stabilizer striking the upper well wall so it takes substantially the entire horizontal thrust from flexible spring member 13. This leaves only a force substantially along the bit axis to be transmitted to the bit, so the bit drills ahead in the direction it is pointed. Second is the restraining force of the spring member.

In the absence of this restraining force, the stabilizer mandrel could continue to tilt with respect to the well bore axis until the universal joint angle limit was reached or until this joint was jammed into the well wall. This would occur, for example, if a universal joint was substituted for the spring member above the stabilizer. If the universal joint is jammed against the well wall, rotation of the universal joint tends to make this joint crawl around the well, thus pointing the bit in directions other than back toward vertical. As explained later in more detail, if an angle-limiting mechanism is used with the universal joint, and if the limiting angle is reached, a side thrust is applied to the bit, partially counteracting the tendency for the bit to drill in the direction it is pointed. With the spring member above the stabilizer, however, tilting of the stabilizer mandrel to the well axis is limited by the spring action of the tubular spring member 13. This is the reason why the flexible element above the stabilizer must be a spring member.

If a spring joint is used below the stabilizer, however, this member must bend from the angle of the stabilizer mandrel at one end, to the angle of the bit axis at the other end. This bending causes the Spring member to drive the side of the bit against the upper wall of the well, thus counteracting the desired return of the bore hole toward vertical. it will be apparent, for this reason, that the flexible element below the stabilizer must be a universal joint and not a spring member.

Still another factor should be considered in connection with the possibility of using a spring member below the stabilizer. All members of the drilling string must be quite strong in order to transmit the large torque and vertical thrust. Thus, any spring member must be very strong and stiff. Such a strong stiff member cannot be bent through much of an angle in a short distance between the stabilizer and bit. A long spring member below the stabilizer requires a small angle between the stabilizer mandrel and bit axis. As a result, the rate of return toward vertical may be very slow. In fact, in some areas the factors driving the well off vertical can easily exceed the ability of a spring member below the stabilizer to return the drilling direction toward vertical. The distance between a universal joint and the bit, on the other hand, can be made very short so the angle between the stabilizer mandrel and the bit axis can be relatively large. In practice, it has been found advisable to connect the bit directly to the bottom of the universal joint. A short sub may be used if desired, however, to attach the bit to the universal joint.

With the application of weight, caused by lowering the drill pipe until the bit bears against the bottom of the hole, the spring member is flexed to a greater degree, moving the universal joint farther toward the high side of the hole. Therefore, for each weight there is a given fixed position of the universal joint relative to the center line of the hole. For each weight the upper part and lower part of the universal joint must assume an angle with respect to each other, this angle being greater for higher weights on the bit. The result is that at higher weights on the bit, in a highly slanted hole, the bit axis will be turned to a more nearly vertical position. This will provide a greater tendency to turn the well back toward vertical at higher weights on the bit.

A comment seems advisable regarding the function of the apparatus using a spring joint, stabilizer and universal joint in a nearly vertical Well. Even in such a well, a high weight on the bit causes the drill string to buckle sufficiently to force the drill collars against the well wall. This means the spring joint is flexed, the universal joint is thrown otf center in the well and the bit is actually pointed away from vertical. In a vertical well, however, there is no force holding the drill collars for any longer time against the east wall of the well, for example, than they spend against the west, north or south wall. Thus, the bit drills slightly off vertical, but for an equal length of time in all directions so the eflccts cancel, resulting in a vertical well. When the well is thrown slightly oif vertical by some cause such as hard tilted formations, however, the drill collars spend more time on the lower side of the well. This causes the bit to be pointed back toward vertical a larger percentage of time than it is pointed away from vertical, thus turning the well back toward vertical. It will be obvious, therefore, that the apparatus using the spring joint, centralizer and universal joint can be used to maintain a well vertical in crooked hole country as well as to turn it back toward vertical after deviation from vertical has occurred.

As mentioned above, the entire drilling string must transmit the entire torque and weight applied to the bit. Universal joints are one common way of transmitting torque through an angle, but few universal joints are designed to transmit much thrust. In drilling wells a thrust in the range of 50,000 or 60,000 pounds may be carried through the joint to the bit. This thrust must be transmitted by .a universal joint sufficiently small in diameter to provide a large clearance in a Well bore since the joint usually operates olf center as shown in FIGURE 1. The area through which the thrust and torque can be transmitted is further limited by the requirement of a central opening through which drilling fluid can be circulated to the bit.

An exploded view of the three principal members of my universal joint which meets these requirements, is shown in FIGURE 2. The central member of this assembly is a thick disc 21. On one face of this disc is a ridge 22 having a cylindrical surface 23 facing away from the disc. This ridge forms a portion of a cylinder, the portion being half a cylinder or less. On the opposite face of disc 21 from ridge 22 is a second ridge 24 having a cylindrical surface 25 facing away from the disc. The axis of ridge 24 is at an angle of about to the axis of ridge 22.

The other two principal members of the universal joint are bearing members 26 and 27. These have cylindrical grooves 28 and 29 respectively which mate with ridges 22 and 24 respectively. The grooves and ridges provide the bearing surfaces of the universal joint. The grooves are shallower than the ridges are high, so the bearing members 26 and 27 can rock a few degrees, for example, 4 or 5 degrees, on the bearing surfaces before the faces of the bearing members contact the faces of the disc. By making disc 21 thick, to transmit torque and thrust from ridge 22 to ridge 24, and by making these ridges massive to transmit torque and thrust to bearing members 26 and 27, a universal joint sufficiently rugged for my purposes is provided even though liquid passages 31, 32 and 33 are provided through members 26, 21 and 27 respectively for circulation of drilling fluid to the bit.

In FIGURE 3 the three principal members 21, 26 and 27 are shown assembled with the other elements of the universal joint. The top of upper bearing member 26 is provided with radial ridges 35 and grooves 36. These mate with corresponding grooves and ridges in a top member 37. Top member 37 is provided with a pin 38 for connecting the universal joint to other equipment such as the stabilizer mandrel of the apparatus shown in FIGURE 1. Connected to top member 37, preferably by welding, is a skirt 41 which encloses the remainder of the universal joint itself and extends on down around a bottom shaft 42. Torque is transmitted from bearing member 27 to shaft 42 through radial ridges 43 and grooves 44. A flange 45 on shaft 42 provides a circular groove 46 between flange 45 and bearing member 27. A packing ring 47 of a resilient material such as tetrafluoro ethylene polymer provides a seal between skirt 41 and bearing member 27. A metallic ring spring 48 is preferably provided to aid the sealing action. The space above seal 47 is preferably filled with a lubricant such as mineral oil. This is introduced through one of openings 51 and 52, the other opening being used as a vent during the filling operation.

The assembly is held together while raising and lowering the drilling string in the well by means of split retainer sleeve 53. Sleeve 53 is held to skirt 41 by balls in race 54 formed about half in each of sleeve 53 and skirt 41. The balls are added or removed through an opening in skirt 41 closed by plug 55.

Shaft 42 may extend to any desired distance below skirt 41. The drilling bit is, of course, attached directly or indirectly to the bottom of the shaft 42 as shown in FIGURE 1.

The passage for drilling fluid through the universal joint is sealed by tube 56 which is preferably of resilient materials such as rubber. The tube is held in place by an upper lip 57 resting on shoulder 58 in top member 37. The top of tube 56 should be held in place by a metallic flanged tube 59 as shown in FIGURE 3.

While the described universal joint is greatly preferred where the torque and weight to be carried are high, other types of joints can be used for lower torques and weights. For example, the type of universal joint used for hollow drive shafts in automobiles and in US. Patent 1,902,174

Lewis, may be used. Ball and socket joints such as that shown in U.S. Patent 2,016,042 Lewis may also sometimes be used if the torque to be transmitted is small.

Few dimensions of the apparatus can be considered really critical. The most critical one is the diameter of the stabilizer or centralizer. This diameter should be at least about 95 percent of the bore hole diameter and should preferably be even closer to the well diameter. Smaller stabilizer diameters drop the center of the stabilizer too far below the center line of the well so the end of the stabilizer mandrel attached to the universal joint may actually be below the center of the well rather than above it. The use of a reamer as a stabilizer may be advisable to insure that the stabilizer center is at the center of the well. The reamer diameter may be only slightly larger, or not any larger at all, than the well diameter and still perform the desired function.

When the diameter of the stabilizer is said to be substantially as great as the well diameter this generally means it should be at least about 95 percent of the well diameter. By careful adjustment of dimensions a somewhat small stabilizer can sometimes be used. The important point is that in a slanted hole, the stabilizer should be large enough to place the center of the universal joint at a point above the center line of the well so the bit will be pointed back toward vertical. In the case of an underreamer-type stabilizer, which is not circular, the diameter should be considered the diameter of the smallest circle which can be circumscribed about the largest part of the reamer elements.

The next most critical factor is the flexibility of the tubular spring joint. This member must be more flexible than the drill collars or the drill collars will bend more than the spring member, causing the axis of the stabilizer mandr l to assume a position very close to the axis of the well. The spring member must, of course, be sufiiciently strong to transmit the desired torque and weight on bit from the drill collars to the stabilizer mandrel. If both the drill collars and the tubular spring member are of the same material, and have substantially the same internal diameter, then the limber member may simply be a drill collar section having an external diameter somewhat smaller than the external diameter of the regular drill collars. For example, if the regular drill collars are mild steel collars with an external diameter of about 7 inches, then the tubular spring member may be a mild steel drill collar having an external diameter of about 6 inches. If other metals or alloys such as aluminum or nickle-copper alloys (Monel) are used to permit use of magnetic orienting eqripment inside the section, for example, the modulus of elasticity of this metal or alloy should be taken into consideration in selecting an appropriate diameter.

The length of the tubular spring member should generally be at least about feet to avoid excessive flexing of this member as it rotates and thus insures a longer life for the member. Shorter spring members may be used in some cases if desired, however.

The universal joint should be considerably smaller than the well diameter so it can be displaced toward the side of the well without touching the wall. A universal joint diameter about 70 to about 90 percent of the well diameter is preferred for this reason.

Use of the apparatus shown in FIGURES 1 to 3 to drill a vertical well will be better understood from the following example. A well in Wyoming was drilling at about 4900 feet. The deviation of the Well from vertical had increased to more than 5 degrees in spite of decreases in weight on the bit until it was only about 7500 pounds. At this very low weight on bit, the drilling rate had decreased to only about 2 feet per hour. An apparatus substantially as shown in FIGURES l to 3 Was then installed just above the bit. The apparatus used in this test differed from that in the drawing by the use of pins for transmitting torque instead of the radial ridges 35 and 43 as shown in FIGURE 3. The weight on bit was increased til to about 25,000 pounds, thus increasing the drilling rate to almost 6 feet per hour while the deviation of the well from vertical decreased to only about 4 degrees. Further increase of the weight on bit to about 45,000 pounds increased the drilling rate to a little over 7 feet per hour. After drilling about 200 feet in a little over 30 hours, the tool was withdrawn from the well to replace the bit. The only difficulty with the tool itself was that some of the torque-transmitting pins had sheared. The design was changed to that using the radial ridges to overcome this difficulty.

The dimensions of interest in this field test were as follows:

Angle limit of universal joint degrees 1.5 Well diameter inches 9 Stabilizer diameter ..-do 8% Length of tubular spring member feet 2 5.48 CD. of tubular spring member inches 5 CD. of drill collars do 7 Distance stabilizer to hit feet 3 OD. universal joint inches. 8

This example illustrates several points. One is that the tool can be used to decrease the deviation of the well from vertical. Another is that the apparatus can be used in regular drilling operations to permit fast drilling of straight holes in areas where crooked holes usually result from fast drilling.

At the highest weight of 45,000 pounds on the bit, the stops which limited the angle which the universal joint could assume came in contact and therefore the toolwas only partly effective. When the stops came together a side thrust was applied to the bit. This side thrust tended to force the bit to drill away from vertical, thus partly counteracting the effects of pointing the bit back toward vertical. This side thrust, plus the natural tendency of the formation to push the bit away from vertical, were enough to increase the deviation of the well from vertical back to about 5 degrees.

In the particular example given above, it was desired to increase the wei ht on the bit, and thus increase the drilling rate, without increasing the deviation of the well from vertical. Up to a weight of 45,000 pounds the tool not only permitted an increase of weight on the bit, but at the same time actually permitted a decrease in the deviation from vertical. In this particular case the increase of deviation back up to about 5 degrees at 45,000 pounds on the bit was undesirable. In many cases, however, it is desired to maintain a certain angle of deviation from vertical in a directionally drilled well. The example shows that this is possible by limiting the universal joint to a small bending angle and applying enough weight to the bit to cause the universal joint stops to come together.

Another reason for limiting the bending angle of the universal joint is to prevent the tool from causing too rapid a return of the well to vertical. A rapid change of well angle is known as a dog leg and should be avoided since it can cause undesirably high stresses in the drill pipe, well casing, and even the production tubing and equipment.

In some cases, crooked hole conditions are so bad that even my tool will not give the desired degree of correction. In order to cope with such conditions, as well as for other reasons, the apparatus shown in FIGURE 4 was designed. In this apparatus a ported plate is attached to the top portion of the universal joint. This plate supports rigid member 61 which extends through members 26, 21 and 27 of the universal joint and into hollow shaft 42. In this case the lower portion of shaft 42 is closed except for passages 62. Preferably these passages are restricted by orifices 63. A piston 64 is exposed to each passage 62 so that pressure in the passage forces piston 64 outwardly to provide a lateral force against split sleeve 53 and skirt 4!. A least 3 pistons are substantially uniformly placed around the periphery of shaft 42. This mechanism is described in more detail in my U.S. patent application 331,158 filed Dec. 17, 1963, except that in that case no universal joint was used and the rigid member 61 in FIGURE 4 of the present apparatus was a pendulum in the apparatus described in the patent. The apparatus shown in FIGURE 4 is preferred for my purposes. Most of the apparatus in the prior art which use a pendulum to actuate pistons to give a side thrust in a desired direction, can be similarly adapted, however. It is only necessary to use in place of the pendulum of the prior art, a rigid member attached to the upper portion of my universal joint. An example of such other apparatus is found in US. Patent 3,141,512 Gaskell et al.

The apparatus shown in FIGURE 4 can be used in various ways. For example, it can be used with a centralizer and spring joint as shown in FIGURE 1. In this case the various pistons 64 may be exposed to passages 62 so that the side thrust is toward the top side of the bore to cause the bit to drill more nearly in a vertical direction. This arrangement can also be used to change the direction of deviation to a more desirable direction by exposing the pistons to passages which will provide a side force pushing the bit in the desired direction.

Another use of the side thrust universal joint of FIG- URE 4 in the assembly of FIGURE 1 is in wells deliberately deviated from a vertical direction. Control of the direction of side thrust and weight on bit can be used to cause the bit to drill not only at a predetermined angle, but also in a predetermined direction.

It should be emphasized that the side thrust universal joint should be used with the assembly shown in FIGURE 1 after the well has been deviated to approximately the required angle from vertical. Such a well, if drilled with the ordinary drill collars directly above the bit, tends to increase its angle from vertical because of the drill collars lying along the lower side of the well. The last collar above the bit is necessarily flexed since the center of the bit is in the center of the well while the centers of the drill collars are below the center of the well. The assembly in FIGURE 1 is then used to prevent further deviation from vertical as well as to control the horizontal direction of drilling. Until the Well reaches the desired angle from vertical, the side thrust universal joint can be used without the centralizer and limber spring joint to increase the angle of deviation from vertical while controlling the horizontal direction of drilling.

In summary, my apparatus can be used in three combinations. One is a tubular spring joint, a stabilizer, and a universal joint with a side-thrust mechanism. A subcombination of this is the tubular spring joint, stabilizer and universal joint omitting the side thrust mechanism. The other subcombinatic-n is the universal joint with the side thrust m chanism omitting the centralizer and tubular spring joint.

The descriptions given above are presented by way of example only. I do not wish to be limited to these examples but only by the following claims.

I claim:

1. Apparatus for drilling wells in a desired direction comprising:

a drilling bit,

a universal joint attached to said bit,

at least 3 pistons in the lower portion of said universal joint, said pistons being distributed substantially uniformly around the periphery of said lower portion, moving substantially radially and being actuated by means, including a rigid member attached to the upper portion of said universal joint, to apply a side thrust in the desired direction to said bit as the bit rotates,

a stabilizer attached to said universal joint, said stabilizer including an enlarged portion having a diameter substantially as great as the well diameter,

a tubular spring member attached to said stabilizer, said tubular spring member being sufficiently strong and still to transmit the desired torque and weight to the bit,

and a drill collar attached to said tubular spring memher, said drill collar being less flexible than said tubular spring member,

a passage being provided through said drill collar, tubular spring member, stabilizer and universal joint to conduct drilling fluid to said bit.

2. The apparatus of claim 1 in which said universal joint comprises:

a disc,

2. first ridge on one face of said disc, said first ridge having a surface in the form of no more than one-half a cylinder,

a first bearing member having a first groove mating with said first ridge, said first groove having a depth less than the height of said first ridge,

a second ridge on the opposite side of said disc from said first ridge, said second ridge having a surface in the form of no more than one-half a cylinder,

the axis of said first ridge and said second ridge being substantially at an angle of degrees to each other,

a second bearing member having a second groove mating with said second ridge, said second groove having a depth less than the height of said second ridge,

means for holding said bearing members and said disc together,

means for transmitting torque to and from said bearing members,

and means for sealing the passage through said bearing members and disc.

3. Apparatus for drilling vertical Wells comprising:

a drilling bit,

a universal joint attached to said bit,

a stabilizer attached to said universal joint, said sta bilizer including an enlarged portion having a diameter substantially as great as the well diameter,

a tubular spring member attached to said stabilizer, said tubular spring member being sufiiciently strong and still to transmit the desired torque and weight to the bit,

and a drill collar attached to said tubular spring men her, said drill collar being less flexible than said tubular spring member,

a passage being provided through said drill collar, tubular spring member, stabilizer and universal joint to conduct drilling fluid to said bit.

4. The apparatus of claim 3 in which said universal oint comprises:

a disc,

21 first ridge on one face of said disc, said first ridge having a surface in the form of no more than onehalf a cylinder,

a first bearing member having a first groove mating with said first ridge, said first groove having a depth less than the height of said first ridge,

a second ridge on the opposite side of said disc from said first ridge, said second ridge having a surface in the form of no more than one-half a cylinder,

the axis of said first ridge and said second ridge being substantially at an angle of 90 degrees to each other,

a second bearing member having a second groove mating with said second ridge, said second groove having a depth less than the height of said second ridge,

means for holding said bearing members and said disc together,

means for transmitting torque to and from said bearing members,

and means for sealing the passage through said bearing members and disc.

5. Apparatus for drilling wells in a desired direction comprising:

a drilling bit,

a universal joint attached to said bit,

at least 3 pistons in the lower portion of said universal joint, said pistons being distributed substantially uniformly around the periphery of said lower portion, moving substantially radially and being actuated by means, including a rigid member attached to the upper portion of said universal joint, to apply a side members and disc.

It) a disc,

a first ridge on one face of said disc, said first ridge having a surface in the form of no more than one half a cylinder,

a first bearing member having a first groove mating thrust in the desired direction to said bit as the bit With said first ridge, said first groove having a depth rotates, less than the height of said first ridge, and a drill collar attached to said universal joint, 21 second ridge on the opposite side of said disc from a passage being providel thrgulglh saiiid drill collalrJ and said1 firfst ridge, said secorgd ridge 1hazing ai sgrface universa joint to con uct ri ing uid to said it. 1n tie orm o no moret an one 1a a cy in er, 6. The anparatus of claim 5 in which said universal the zgiis of slzliid first ridgle Said second ridghe biing oint comprises: su stantia y at an ang e 0 degrees to eac 0t er, a disc, a second bearing member having a second groove mata first ridge on one face of said disc, said first ridge ing With said second ridge, said second groove having having a surface in the form of no more than one a depth 1558 than the height of Said SeCQnd ridge, half a cylinder, 8 means for holding said bearing members and said disc a first bearing member having a first roove mating together,

with said first ridge, said first groove lia i a d th means for transmitting torque to and from said bearing less than the height of said first ridge, members, a second ridge on the opposite side of said disc from and 3 d p ge o gh aid bea ing members said first ridge, said second ridge having a surface in and discthe form of no more than one half a cylinder, References Cited the axis of said first ridge and said second ridge being substantially at an angle of 90 degrees to each other, UNITED STA:TES PATENTS a SBCOHd bearing member having a second groove mat- 1,902,174 3/1933 LeWlS 175-61 X ing With said second ridge, Said second groove hav- 1,971,480 8/1934 Ear ey 175-61 X mg 8. depth 1688 than the height Of said second ridge, 2,813,409 11/1957 WOICOH 6417 means i r l ng id bearing members and said disc $332; x32; gq g toget er, Us Y L means for transmitting torque to and from said bearing g 1-1- X mem ers, as e 75-73 X and means for Sealing the passage through id b i 3,243,001 3/ 1966 Vincent -73 CHARLES E. OCONNELL, Primary Examiner.

7. A universal joint suitable for use in a rotary drilling 35 NILLE C. BYERS, Examiner.

string for drilling wells comprising: 

